"""
Created on 20 August 2017

Loans Summary

Validation

@author: Peter Wilson
"""
import re
import csv
import argparse
import collections
from datetime import datetime


def csv_to_dict(loans_csv):
    """Convert loans csv to
    Python dictionary"""
    loans_dict = csv.DictReader(open(loans_csv))
    return loans_dict


def dict_to_agg_dict(loans_dict):
    """Aggregate loans by
    (Network, Product, Month)"""
    agg_dict = collections.OrderedDict()
    for row in loans_dict:
        network = re.sub(r"'", '', row['Network'])
        product = re.sub(r"'", '', row['Product'])
        # assumed month per year to be aggregated
        month = re.findall(r'([A-z]+?-d{4})', row['Date'])[0]
        # assumed currency rounded to closet rounded number
        currency = float(row['Amount'])
        dict_key = (network, product, month)
        agg_dict.setdefault(dict_key, []).append(currency)
    return agg_dict


def agg_dict_to_lists(agg_dict):
    """Convert aggregated dictionary
    to Python list of lists"""
    summary_list = []
    for key, values in agg_dict.iteritems():
        values_list = list(key)
        currency_sum = sum(values)
        counts = len(values)
        values_list.insert(len(values_list), currency_sum)
        values_list.insert(len(values_list), counts)
        summary_list.append(values_list)
    return summary_list


def output_csv_summary(summary_list, output_csv_folder):
    """Write aggregated results
    into output csv"""
    current_date = datetime.today().strftime("{0}{1}{2}".format("%y", "%m", "%d"))
    csv_name = "{0}_{1}.csv".format("Output", current_date)
    output_csv = "{0}\{1}".format(output_csv_folder, csv_name)
    print("Writing {0} to {1}".format(csv_name, output_csv_folder))
    csv_header = ["Network", "Product", "MonthYear", "Currency", "Count"]
    with open(output_csv, 'wb') as csvfile:
        csvwriter = csv.writer(csvfile)
        csvwriter.writerow(csv_header)
        for row in summary_list:
            try:
                csvwriter.writerow(row)
            except UnicodeError as e:
                print(e)


def validate_loans(loans_csv, output_csv_folder):
    """Validate loans summary from
    accounts with system"""
    loans_dict = csv_to_dict(loans_csv)
    agg_dict = dict_to_agg_dict(loans_dict)
    summary_list = agg_dict_to_lists(agg_dict)
    output_csv_summary(summary_list, output_csv_folder)


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Validate accounting loans summary against system')
    parser.add_argument('--loans_csv', metavar='path', required=True,
                        help='path to input loans csv')
    parser.add_argument('--output_csv_folder', metavar='path', required=True,
                        help='path to output csv folder')
    args = parser.parse_args()
    validate_loans(loans_csv=args.loans_csv, output_csv_folder=args.output_csv_folder)